/// CASTING A STRING TO A NUMBER
/// @param {Number} $number
/// @param {Number} $unit
/// @author Hugo Giraudel
/// @link http://hugogiraudel.com/2014/01/15/sass-string-to-number/

@function unit-length($number, $unit) {
  $strings: 'px' 'cm' 'mm' '%' 'ch' 'pica' 'in' 'em' 'rem' 'pt' 'pc' 'ex' 'vw'
    'vh' 'vmin' 'vmax';
  $units: 1px 1cm 1mm 1% 1ch 1pica 1in 1em 1rem 1pt 1pc 1ex 1vw 1vh 1vmin 1vmax;
  $index: index($strings, $unit);

  @if not $index {
    @warn "Invalid unit `#{$unit}`.";
    @return false;
  }

  @return $number * nth($units, $index);
}
